GSoC 2009: GHOP - Eleventh Week Status Update!

Hello everyone,
A week of frustrations come to an end. The goal for last week was to get the Tag system in place for GHOP. The goal included giving the Program Admin to Add/Delete and Edit Tags. And you might already know that we are using a modified version of Taggable-mixin for tagging in Melange.

Although Adding and Deleting tags looked very trivial to me, edit was not so trivial. The first reason being, the key name for the tag stored in the Datastore used the tag name. So every time you edit a tag a new key needs to be created, but all other properties must be retained, so tag must be copied to the new entity. Also over and above this, on the UI side I was not even sure how to allow Program Admin to Add/Delete and Edit a tag in the same interface. After a lot of struggling and battles within and frustrations, I thought for a GHOP Program number of types of Program defined tags are fixed, one is for Task Difficulty level and other is for Task Type. So I created 2 pages, one for each where one could do all the 3 actions(Add/Edit/Delete).

For accomplishing this per Task page, I have used a JQuery plugin called, in-place-edit. This allows us to edit a tag in-place. So one can click on Add button to add new tags, and make the contents of the tag empty to delete it or edit the tag name. The editing of the tag name automatically copies the old Tag entity to the newly created Tag entity. And each creation, edit and delete happens via AJAXy calls, so one need have to save the changes after editing the page completely. Program Admin can just exit the page.

Once I solved this problem, a new problem arose. Usually tags have to be sorted in some order, say for example for difficulty level tags, it must be sorted from easiest to hardest. But tags need not be created in the same order. For example, Program Admin might initially think, only Easy, Medium and Hard are sufficient, but might later realize a Trivial difficulty level is required. So this needs to be ordered in the order enforced by the Program Admin. Once again I had to goto JQuery for help. I used JQuery UI's sortable plugin already in Melange code base to drag and drop sort the list of tags. So ordering is implemented as well.

After this, the interface to Add Tags to create/edit tasks had to be added. For a difficulty level tag, it is a normal drop down. But a Task can be of multiple types, like Documentation and Translation. So for this I have used an HTML Multiselect box. Also there is a text box for adding arbitrary tags. At the moment, these two types of tags are merged and stored as the entities of same TaskTypeTag model in the datastore with mandatory property=True for Task type tags and False for arbitrary tags. But Lennie wanted this implementation to be changed and separate them into 2 models. This requires a good amount of re-work. I will do it this week.

After all these, I started working on Search for tasks and happily created multi selects for Organizations, Task status, Difficulty Level, Task Type and started generating queries for them. It was then Lennie, made me realize that there can be only 30 subqueries per query. So this kind of search mechanism won't work. I have currently stalled my work on it. I am thinking of work arounds to this. Once we get a fair idea of what to do, I will resume the work on Task search.

Amidst all these work, I have been fixing bugs, making some implementation changes like Task state transitions etc. This week, I will be mostly working on writing a starter manual, fixing bugs and student data model conversion to include whether student belongs to High School or University.

Last but not the least, all my work till now is available on my demo instance at, http://melange-madhusudancs.appspot.com